Journal / Practice
Is Pilates strength training
Springs are resistance, so technically yes. The honest answer needs a bit more nuance than that.
People who lift weights ask this a lot, usually while deciding whether Pilates can replace a gym session or whether it is just a stretch class with better marketing. The short answer is that it is genuine resistance training. The longer answer explains where that stops being enough.
Why the answer starts as yes
The springs on a reformer, tower, chair, or Cadillac provide real, adjustable resistance, and resistance training is how strength gets built, whichever apparatus supplies it. For someone starting from very little base fitness, or coming back from time off, Pilates alone can build noticeable strength surprisingly quickly.
Where it runs out of road
Adaptations from serious lifting eventually need more load than springs can provide. A loaded barbell can be increased almost without limit. A spring cannot, and most Pilates apparatus tops out at a resistance that is modest by gym standards. Someone chasing continued strength gains, or working on bone density, will hit a plateau on springs that heavier, external load would keep pushing past.
Strength keeps adapting as long as the load keeps increasing. Springs run out of increases before muscles run out of appetite.
What Pilates trains that barbells do not
Control through a full range of movement, strength at the end of a range rather than just in the middle of it, and the small stabiliser muscles around a joint that big compound lifts tend to skip over entirely. These are not lesser forms of strength. They are the ones that keep a heavily loaded lift safe in the first place, and the ones most gym programmes never train directly.
The two do not compete for the same job. Pilates for control and the smaller muscles, heavier training for maximal load. Someone who wants both eventually ends up doing both, not choosing one and quietly resenting the other.